Update call.o to hvc_call.o

As a part of VHE related patches in hafnium, this file was changed.
Update linux driver accordingly.

Signed-off-by: Raghu Krishnamurthy <raghu.ncstate@gmail.com>
Change-Id: I0ab8e9fdcf59db4ecb98d120de6c3f6875752984
diff --git a/Makefile b/Makefile
index 3b0b57b..0f234fe 100644
--- a/Makefile
+++ b/Makefile
@@ -19,7 +19,7 @@
 obj-m += hafnium.o
 
 hafnium-y += main.o
-hafnium-y += vmlib/aarch64/call.o
+hafnium-y += vmlib/aarch64/hvc_call.o
 hafnium-y += vmlib/ffa.o
 
 ccflags-y = -I$(HAFNIUM_PATH)/inc/vmapi -I$(M)/inc